1. Technical Field
The present invention relates to a method for operation of a wind energy installation having a rotor which can be driven by wind and has at least one rotor blade, having a generator for conversion of the mechanical energy of the rotor to electrical energy, and having a tower on which the rotor is arranged. The present invention also relates to a wind energy installation which is operated using this method.
2. Prior Art
Wind energy installations are subject to particularly high loads in strong winds. Wind energy installations are generally designed such that, in the extreme, they can withstand wind speeds which correspond to those of the so-called once-a-century gust.
However, even in Europe, extreme wind conditions are occurring ever more frequently, with wind speeds which may be above the once-a-century gust. Furthermore, for example in the USA or Australia, there are wind energy installation locations at which it is possible for cyclones or the like to occur. Cyclones can cause wind-dependent forces acting on the wind energy installation which considerably exceed the loads resulting from a once-a-century gust.
Guys are known for stabilization of buildings in general against external influences, in particular wind. In this case, a plurality of cables, chains or the like which originate from the building to be stabilized are tensioned, and are anchored in the ground. However, the permanent use of guys such as these for wind energy installations would have considerable disadvantages. This is because wind energy installations are subject to dynamic loads. The forces introduced into the wind energy installation as a result of the guys—particularly as a result of the dynamic loads on the wind energy installations—would lead to fatigue problems at those points or in those areas of the wind energy installation into which the forces are introduced.